Abstract: In contrast to almost no H-abstraction reactivity of the ground-state para-substituted benzyl radicals@-X-benzyls: X= CN, CI, F, and OCH3) toward 1, 4-cyclohexadiene (CHD), a significant fluorescence quenching by CHD in hexane at room temperature was confirmed for their fluorescent excited states, which may be assigned to 2B2 for p-cyanobenzyl and 1A2 for the other three pX-benzyls. The quenching reveals a marked substituent effect: the ...
